code: def test_dotvecmat_vector_times_identity_matrix():
      A_numpy = np.array([[1, 0], [0, 1]])
      A_river = {(0, 0): 1, (0, 1): 0, (1, 0): 0, (1, 1): 1}
      x_numpy = np.array([1, 1])
      x_river = {0: 1, 1: 1}
  
      numpy_dotvecmat = x_numpy.dot(A_numpy)
      river_dotvecmat = utils.math.dotvecmat(x_river, A_river)
  
      assert numpy_dotvecmat[0] == river_dotvecmat[0]
      assert numpy_dotvecmat[1] == river_dotvecmat[1]
  
file_path: river/river/utils/test_math.py
imports: from __future__ import annotations
  import numpy
  from river import utils
label_desc: Use image node_id 5 for calling a global function with example usage: test_dotvecmat_vector_times_identity_matrix() without return types